This invention relates generally to inflator devices such as for use in inflatable safety restraint installations and, more particularly, to an initiator assembly whereby an initiator is joined to an inflator device.
Inflatable safety restraint installations typically use an inflator device to produce inflation gas for inflating an inflatable airbag in the event of a collision. The inflator device often includes a gas generant material stored within an inflator device housing and a preformed initiator in combination with the housing that actuates the gas generant material. Suitable initiators typically include a reactive charge in combination with one or more electrical connectors. A signal sent through the electrical connector(s) actuates the reactive charge, which produces reaction products that actuate the gas generant material.
Initiators can be joined directly to an inflator device or initiators can be first joined to an adapter plate, and the adapter plate is joined to the inflator device. Although initiators can be directly joined to any wall of inflator devices, initiators are typically directly joined to base portions of inflator devices. When the initiator is joined to an adapter plate, the adapter plate can, for example, form an inflator device base or a portion of the inflator device base.
Currently, initiators are typically joined to inflator devices or adapter plates by way of one of two techniques. A first technique includes inserting the initiator into an appropriate machined interface and crimping the interface to secure the initiator. Such crimping requires that a precise interface be machined into the inflator device or adapter plate. Crimping is thus relatively expensive and at least some crimping processes are known to have quality control problems.
A second technique involves integrally molding an initiator directly to an inflator device or adapter plate using a moldable material, such as a thermoplastic. Such integral molding is typically less expensive than the crimping method mentioned above. However, typical integral molding processes have disadvantages as well. For example, time-consuming precautions are generally needed prior to subjecting the initiator, which often contains a pyrotechnic reactive material, to the molding operations. Also, integral molding processes typically employ only a single type of plastic material to form the entire molded portion. Plastic materials generally used in such integrally molding processes are desirably resistant to atmospheric moisture and crack resistant. Crack resistance is particularly desirable in an area around an initiator cup, or cap, which ruptures upon actuation of the reactive material. Thus, plastic materials available as molding material are generally limited to materials having a desirable balance of moisture resistance and crack resistance. Another disadvantage of such integral molding processes is that a hermetic seal between the initiator and the inflator device can be difficult to maintain as the thermoplastic expands and contracts during temperature cycles common during installation procedures. Therefore, such integral molding processes often require carefully designed joint geometries that may not be possible in some types of inflator devices.
Thus, there remains a need for an initiator assembly that minimizes or eliminates the need for expensive and complicated machining. Further, there remains a need for an initiator assembly that is less expensive, safer to produce, has the desired strength and provides a desirable seal with the inflator device and for an initiator assembly.